There is no was to copy or merge multiple symbols from one library to another, but you can move them one at a time. Merging libraries requires you to have both libraries on the same machine. You can open your symbols in the Symbol editor and save them to a new library one at a time.
From the Schematic
Footprints can by copied to a new library in a group.
- Place the libraries in your Custom folder
- Select Tools > Symbol Editor
- Select the Open Symbol tool bar button.
- Locate the symbol you want to copy and load symbol.
- Select the Save Symbol toolbar button
- Select library to save into.
- Select OK
- From the layout select Design > Manage Library.
- Select the library that contains the parts you want to copy.
- Go to the footprints section and select all of the footprints you want then select the copy button.
- Go back to the libraries section and select the destination library.
- Move to the footprints section and select the paste button.
I have provided feedback to our development team asking for a library manager for schematic symbols.
Please contact customer support if you have any questions.